Respuesta :

6r + 7 = 13 + 7r ....subtract 7r from both sides
6r - 7r + 7 = 13 + 7r - 7r....simplify
-r + 7 = 13....subtract 7 from both sides
-r + 7 - 7 = 13 - 7...simplify
-r = 6...multiply by -1 to make r positive
r = -6
6r+7=13+7r
6r-7r=13-7
-r = 6
r = -6